fix: cover sub2api model routing 503 cooldown

scripts/platform-infra-sub2api-codex-temp-unsched-contract-test.ts

@@ -29,10 +29,14 @@ assertCondition(!("pool_mode" in credentials), "pool_mode must not be enabled be
 assertCondition(!("api_key" in credentials) && !("base_url" in credentials), "temporary-unschedulable rendering must not include secrets or endpoints", credentials);
 const accountState403Rule = rules.find((rule) => rule.error_code === 403);
 const quota429Rule = rules.find((rule) => rule.error_code === 429);
+const serviceUnavailable503Rule = rules.find((rule) => rule.error_code === 503);
 for (const keyword of ["weekly limit", "less than 10% of your weekly limit left", "run /status for a breakdown"]) {
   assertCondition(accountState403Rule?.keywords?.includes(keyword), "403 rendered rule must preserve Codex weekly-limit account-state keyword", { keyword, accountState403Rule });
   assertCondition(quota429Rule?.keywords?.includes(keyword), "429 rendered rule must preserve Codex weekly-limit quota keyword", { keyword, quota429Rule });
 }
+for (const keyword of ["model_not_found", "no available channel for model"]) {
+  assertCondition(serviceUnavailable503Rule?.keywords?.includes(keyword), "503 rendered rule must catch upstream model-routing failures", { keyword, serviceUnavailable503Rule });
+}
 
 const disabled = renderSub2ApiTempUnschedulableCredentials({ enabled: false, rules: policy.rules }) as {
   temp_unschedulable_enabled?: boolean;
@@ -48,6 +52,7 @@ console.log(JSON.stringify({
     "temporary unschedulable policy renders to Sub2API credential field names",
     "temporary unschedulable rendering follows the input policy without hard-coded policy gates",
     "Codex weekly-limit prompt keywords render into 403 and 429 cooldown rules",
+    "upstream model-routing failures render into the 503 cooldown rule",
     "disabled policies clear runtime rules",
   ],
 }));